1. Field of the Invention
The present invention relates to a window device for use in a motor vehicle, in particular, to a window device for use as a sunroof in a motor vehicle.
2. Description of the Related Art
For a long time, it has been known that a window device for use as a sunroof in a motor vehicle is made of a polymethyl methacrylate resin or a polycarbonate resin, since this kind of material has a very small specific gravity and thus it is considered suitable for use as an appropriate material of a light transmissible member for manufacturing a light weight motor vehicle. Where a window of a motor vehicle is made of a synthetic resin, since a synthetic resin has a lower elastic modulus than a glass material, the resin material is usually combined with a reinforcing material along the edge portions of the window so as to obtain a desired reinforcement to prevent a possible bending and twisting.
However, there has been a problem with a window made of a synthetic resin. That is, a resin window panel has a comparatively large deformation amount caused by a thermal expansion due to a temperature change. To cope with the above problem, it has been suggested that a resin window panel be laterally movably combined with reinforcing members which are to be secured on the vehicle body so as to form a thermal expansion absorbing structure which is cable of absorbing a thermal expansion caused by a temperature change. This kind of thermal expansion absorbing structure may, for example, be found in Japanese Unexamined Utility Model Publication No. 5-16419.
As disclosed in Japanese Unexamined Utility Model Publication No. 5-16419, a reinforcing member having a U-shaped cross section is movably attached to outer edge portions of a resin window panel with the use of several bolt-nut connection assemblies loosely inserted in several holes formed through the resin window panel. Further, a pair of elastic members are interposed between the inner surfaces of the reinforcing member and the resin window panel to prohibit a possible rattling of the resin window panel and to partially absorb its thermal expansion.
However, with the above conventional structure, since several bolt-nut connection assemblies are used to clamp resin window panel and a pair of elastic members are interposed between the resin window panel and the reinforcing member, a capability of absorbing a thermal expansion of a resin window will vary from one window device to the other because of a fact that a clamping force of a bolt-nut connection assembly will vary depending on an elastic members. Moreover, there is also a possibility that a clamping force of a bolt-nut connection assembly will be different from one connection spot to the other. For this reason, during an operation of assembling a window device, it is necessary to pay attention to ensure that clamping forces on all connection spots are made identical, hence rendering the assembling operation too troublesome.
FIG. 18 illustrates a tilting type window device for use as a sunroof of a motor vehicle, while FIGS. 19 and 20 illustrate some functional elements attached to the resin window panel. A window panel 81 is attached to a sunroof housing by means of a hinge such that the window panel 81 may be easily opened or closed thereon. Further, the window panel 81 is fixed at a predetermined position by means of a locking handle 83. Here, both of the hinge 82 and the locking handle 83 are secured in positions by means of bolts 84 and nuts 85. Further, along an edge of the resin window panel 81, a reinforcing member 86 made of an iron or aluminum is bonded by an urethane adhesive agent 87 to obtain a desired reinforcement. In FIG. 18, an arrow FR shows a front direction of a motor vehicle.
However, since many functional elements and reinforcing members are arranged on the resin window panel 81, a light blocking area is increased, hence causing a decrease in a light transmissible area of the window panel 81.
Namely, in the above conventional structure, each of the hinge 82 and the locking handle 83 is fixed in position by inserting a bolt 84 in a hole 88 formed through the window panel 81 with a seal material 89 interposed therebetween, followed by tightening up a decorative nut 85.
In order to avoid an aesthetically uncomfortable feeling when looking at the window device from a vehicle room, some portions of the resin window panel 81 are made not transparent so as not to expose the hinge 82 and the locking handle 83 to the eyes of a person sitting in the vehicle room. However, it is extremely difficult for a decorative nut 85 not to appear on the upper surface of the resin window panel 81 because of its specific structure, hence resulting in an aesthetically uncomfortable feeling, and causing an uncomfortable wind sound due to the protruding structure of a nut 85 when the vehicle is running at a high speed.
In addition, since the above discussed structure needs to employ a sealing member 89 to seal the bolt hole 88, such sealing member 89 will gradually not give a satisfactory sealing effect with the passing of time, thus resulting in a trouble that rain water may invade through the bolt hole into the inner surface of the resin window panel.